Browsing by Author "Davisan, S."

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Comparative Analysis of Characteristics of Dye-Sensitized Solar Cells Utilizing Extracts of Young vs Mature Leaves of Elaeocarpus Serratus as Natural Sensitizers
(SLIIT, Faculty of Engineering, 2024-10) Davisan, S.; Nupearachchi, C.N.; Perera, V. P. S.
This study addresses the pressing global need for sustainable energy sources by exploring dyesensitized solar cells (DSSCs) as a viable alternative. Specifically, the research focuses on extracting natural pigments from Elaeocarpus serratus (Sri Lankan olive) leaves to enhance the efficiency of DSSCs. These leaves undergo color changes as they mature, presenting opportunities to extract different types of pigments at different ages. Extraction involves boiling pieces of leaves in absolute ethanol to obtain the desired pigments. Further characterization via UV-visible spectroscopy revealed the presence of different absorption bands of pigments in the natural dyes’ extracts. The constructed DSSCs employed these natural dyes, coated on TiO2 films deposited on FTO glass plates as the photoanodes. The liquid electrolyte was I2/I3 - and a platinum-sputtered glass plate served as the counter electrode. Photovoltaic characteristics were evaluated using a computerized PK-IV 100 I-V analyzer under 100 W/m2 illumination. Results indicated the superior performance of DSSCs utilizing young leaf extracts, yielding a short circuit current density (JSC) of 3.950 mA/cm2, open circuit voltage (VOC) of 458.8 mV, and a fill factor (ff) of approximately 0.553 with an efficiency (η) of 1.003%. Conversely, DSSCs utilizing. Mature green leaf extracts exhibited lower performance metrics, with JSC of 2.379 mA/cm2, VOC of 477.5 mV, ff around 0.492, and η of 0.559%. Therefore, the efficiency of DSSC fabricated with young leaf is 56% higher than the DSSC made with mature green leaf extract.
Open Access
Use of Ascorbic Acid Linker in Enhancing the Photovoltaic Performance of CdS/TiO2 Quantum Dot Sensitized Solar Cells
(SLIIT, Faculty of Engineering, 2025-01) Ajward, N.F.; Davisan, S.; Perera, V.P.S.
This study explores the use of ascorbic acid to enhance the photovoltaic performance of CdS/TiO2 Quantum Dot Sensitized Solar Cells (QDSSCs). Ascorbic acid acts as a mild reducing agent, donating electrons to Ti atoms on the TiO2 film, effectively filling oxygen vacancies known to act as recombination centers for photogenerated charge carriers. By passivating these detrimental sites, ascorbic acid facilitates improved carrier transport and reduces recombination, ultimately boosting photocurrent and overall efficiency. QDSSCs fabricated via the Successive Ionic Layer Adsorption and Reaction (SILAR) method were characterized using I-V measurements, Incident Photon to Current Conversion Efficiency (IPCE), Impedance Spectroscopy (IS), and overall power conversion efficiency. The optimized cell incorporated with ascorbic acid demonstrated a remarkable improvement compared to the control, achieving a short circuit current density (Jsc) of 4.863 mA/cm², open circuit voltage (Voc) of 446.1mV, efficiency of 1.368%, fill factor of 24.6%, and maximum power of 0.342mW. Optimization of ascorbic acid absorption time and precursor concentrations resulted an impressive 68.26% enhancement in efficiency (from 0.813% to 1.368%) and increase in maximum power from 0.163 mW to 0.342 mW for 0.64 cm². cell. This study highlights the potential of ascorbic acid as a simple and effective strategy for enhancing the performance of CdS/TiO2 QDSSCs, paving the way for further developments in low-cost and efficient solar cell technologies.